Manufacture of casein



July 31, 1951 P. F. SHARP ET AL 2,562,645

MANUFACTURE oF CASEIN Filed sept. 4. 1947 2 sheets-Sheet 1 5 l R 1 0 mwf @w uw Wh W ,wh n. MMM @d 155 M AMF): @i l//l d am E B O%\\ Nm .\Qm 7^@&%N Mw) g .W.I........H-.......w.uHwhwzknmi, QN .uw TEN ,xfw liv r/.HIIl R July 31, 1951 P. F. SHARP ET AL 2,562,646

MANUFACTURE oF CASEIN Filed Sept. 4, 1947 2 Sheets-Sheet 2 INVENTORS. lPazzzZ/zzo, BY `fo/zfz Patented July 31, 1951 San Francisco, Calif.,assignors to Golden State Companm, Ltd., San Francisco, Calif., acorporation of Delaware Application september 4, 1947, serial No.772,090

19 Claims. l

This invention relates to a method of separating solid materials fromassociated liquids, and particularly solids which can be converted intoer caused to exist as a foam or mass capable of floating on the surfaceof its associated liquid.

O'ne speci'c application of this invention relates to the recovery ofcasein by separating the same from thev whey and impurities afterV theproteinaceous material has been rendered in' soluble and converted to aVfoam which is light enough to iloa't on the whey.

The present invention further relates to a method of- Wa'shin'g solidswhich are in the forin of relatively stable foams and makes possible thefreeing of such solids from adhering material so as to produce ortolr'eoover a relatively pure product therefrom.

According to one embodiment of this inven'- tion, a separation of thesolids and the associe ated liquid is elected after the solids have beenconverted to a foam or a floating mass in a suitable tank or vreceptacleby causing the iloatin'g foam to be displaced laterally along thesurface of the associated liquid and ultimately, by such lateralmovement, to pass out of association with such liquid. Such treatmentcontemplates the simultaneous removal of liquid from the tank orreceptacle by draining the same downwardly or in 'a direction differentfrom that' of the lateral .movement of the solid mass.

In certain flotation separation methods, certain movements are given tothe solids' by the movement of the liquid on the surface of which thesolids are sustained, whereby the liquid and the solids both move in thesame general direction, with the result that the movement of the solidsis dependent upon the movement of the liquid. In theabove-d'escribedembodiment of the present invention, however, the movement of the solidsisv not effected by' a corresponding movement of the liquid, as theliquid is preferably withdrawn` from a point below the liquid level inthe tank or receptacle' in' which the `llctatior'i oe; ours. Accordingto this embodiment of therpres'e ent invention, therefore, 'the iloatingsolid material is displaced laterally across the surface of the liquidand is ultimately removed from the container or receptacle in which theflotation 'oc'- eurs, while the liquid is withdrawn in a diiierentmanner,v in 'a diifer'ent direction, and by diiferent means.

While the lateral movement of the solid mateiial on the sur'faee 'of thliquid 'liiay be effected in various ways, the preferred form of thein'- vention relies on a lateral nievement of the oat'- 2 ing solidmaterial produced by the hydrostatic head of foam oi' by a crowdingaction exerted by' the' new material entering the tank or re"- ceptacleand seeking floating space on the limited surface of thilz'liquidlafforded bythe area of the tank or `receptacle employed. such crowdingaction, when eire'rted en' the foam already present on the surface ofthe liquid, ultimately results the material being'l pushed to the edgeof the tankr over which the curd breaksv in the desired nrianner,lwhereby it is separated and colle'cted'foi use or further processing asmay be desired in any particular case'. I y

Such crowding action` can be accomplished by the mere introduction intoa suitable tank or receptacle of the liquid and solids to be separatedafter the solids have been processed in a man'- ner to render themlioatable on the liquid.A

Y if the solids and liquid are continuously in; troduoed into thereceptacle or tank, the liquid may becontinuously withdrawn from afpoint' bejlo'vv the liquid` level therein, and` the solidsl will becontinuously moved and displaced laterally 'over' the edge'thereof, withthe result that the f' process is carried 'out automaticallyv andcori-'- tinuously, with th separation of. the solids and liquidoccurring at' the same rate that the oon'- stituent parts thereof areintroduced into the tank.-

When treating various substances such as relatively stable foains, as,for instance, cheese Olli/dy Caselli; all'd the like) Washingpe'rati'oii's of a more or less extensive degree are preferablyconducted and canv be carried out by spraying,

washing liquid, such` as water, onto the foam when the foam islv ineither the original separa'- tioh tank` or receptacle or a differenttank'- or receptacle towhich thel mate-rial irl-ay be' passed forwashing after the initial separation treatfment.

Ill O'Ii'e forni of the ilvelltioh, a Ser-les of flota;- tionf may bearranged stepped relation but 'in Suchdis'po'sitoii that the first tankis the highest and each subsequent tank thereafter progressivelyV islower and each tank' in the series is positioned to receive solidsdisplaced from the next preceding taria vIrl such a system, the initialseparation, with or without wash-ing, may be carried out theiirsttaiil,` and thereafter further separationby' washing 'can be' 'accoglie'plis'lied one v'or incre subsequent tanks. The washing-ernay'beaccomplished by using water' or "other" `cle'aifii'rig liquidapplied lineach tank, 'respetively', preferably in?r thejforn of a spray'. 'SuchWashiealbe conducted to the extent ci' required and for as many tanks orby as many separate operations as may be necessary in any particularcase. However, when casein is being produced according to this process,the washing water can be used repeatedly over and over again to greatadvantage, for the reason that by such repeated uses of the washingwater employed only approximately one-twelfth of the quantity of washwater normally required is needed and the concentration of solidstherein that are recovered from the floatable material being Washed canbe increased to a point where the wash water approaches the solidscontent of the original Whey separated from the casein. The productionof such concentration permits the wash water to be mingled and handledwith the whey, as for all practical purposes it is substantially thesame thing. Thus the whey and wash Water can be dried and handledtogether, which, of course,

avoids the necessity of throwing away the wash water and the containedsolids, such as otherwise would be necessary if the concentration ofsolids in the wash water were not increased to a point of producing aneconomical and, usable material. This last advantage avoids the costlysewage disposal problem which is involved where the wash water cannot beprocessed in this manner.

Such repeated washing operations can be conducted by rst applying freshwashing water to the last tank in the series and in using the wash wateras the liquid on which thesolid foam floats. By spraying the water ontothe floating mass of solids, such washing operation is conducted whilethe iioating mass passes laterally on the surface on the moving floatingmass which is there ung dergoing similar treatment. By taking the washAwater from such 4tank and using it as wash water in the next precedingtank and carrying this washing operation on to a required extent aconcentration of solids in the wash water is produced which approachesthat of the whey and at the same time an extremely clean and desira--ble finished product results.

As the solid foam movesdown from one tank to the other, it is presentedto wash water of progressively lower solids concentration or, in otherwords, to water of progressively cleaner jcharacter. At the same time,the wash water is being conveyed in the direction opposite to thepassage of the solid product, whereby it is exposed to a product thequantity of impurities in which is progressively increased. Accordingly,the concentration of solids in the wash water is constantly built up asit passes from one tank to the next and the product becomes cleaner andcleaner.

According to the conventional method of producing high quality casein,the protein is prec ipitated from skim milk with either rennet, acid, orother precipitating agent. When so precipitated, the curd alwayscontains extraneous matter such as salts, lactose, and some occluded but.unprecipitated proteins such as globulin and lactalbumin. Due to thefact that the curd is heavier than the whey it tends to settle towardthe bottom of the treating tank in the form of a large number of smallparticles which become loosely matted together as a bulky mass. Thismass generally settles only to the extent of having a minor portion ofthe liquid in a settling tank as decantable, clear liquid containing nosolid material. In such a process, the whey is then removed bydecantation. However, curd must be washed repeatedly by resuspension toremove impurities, which is an operation requiring large volumes ofwater in addition to being time consuming. Furthermore, such treatmentrequires the installation of large, expensive, and spaceconsumingequipment, such as large tanks provided with agitators and drain racks,all of which are difficult to maintain and clean. Such old and knownprocess for producing casein also necessitates manual handling of thecurd, which is undesirable. In applicants copending application, SerialNo. 612,965, led Aug. 27, 1945, now abandoned, there is disclosed amethod for recovering casein from milk. In that process, milk, acid, andair are mixed simultaneously and the mixture is caused to issue from themixing device as a froth which is fed to and collected in a receptacleor tank. In the tank the froth quickly separates into a whey layer and asolid layer made up of a proteinaceous foam which floats on the surfaceof the whey. This foam layer is then preferably collected by a paddledevice which propels the foam along the surface of the whey to a removalpoint. Next, the foam either is pushed onto an inclined moving belt or ascreen, or is trapped between moving paddles traveling up an inclinedsurface and thus removed from contact with the whey. The whey is drainedfrom the receptacle and the curd, after separation, is washed by waterwhich is preferably sprayed into the foamy mass, collected in theabove-described manner, and held on a screen or the like. Certainmechanical complications involved in the washing of casein foam when thesame is carried on a screen or the like markedly reduce the efficiencyof that process which otherwise is commercially satisfactory.

Casein produced by the method described above and claimed in saidcopending application, is of low density, or in other words, it has alarge volume per unit weight. Consequently, when such foam is depositedin a tank, a large surface area must be provided so that the foam willspread in a layer thin enough to permit proper drainage and thoroughwashing. The result is that large or multiple paddle conveying devicesmust be employed. The cost of operating such oversize equipmentconstitutes a portion of the total operating cost, which is undulylarge.

The present invention overcomes many of the objectionable features ofthe prior art and permits the continuous production of an edible proteinof the highest quality without requiring manual manipulation of curd andwithout requiring the use of expensive or cumbersome machinery forcollecting and washing the foam-like curd.

It is, therefore, an object-cf the present invention to provide a methodof separating coagulated proteins in the form of foam or froth, whetherprecipitated with acid, rennet, or other precipitating agent, from itsassociated liquid in a way which eliminates mechanical conveyingequipment.

It is a further object of the present invention to provide a method foreffectively conductinga countercurrent washing of floating casein in theform of a foam-likemass.

atea-,cie

fA still further y'object is fito provide :a "process 'winch can bev'corid-tlietedlwith fthe usent-simple equipment, which isea'sy tocleanly-and which improves the sanitation of the operation. Anotherobject lis "to-providea` method accordingto which the-washingmedium/permeateslthe casein material and comes-in contact withiindividual particles ofthe mass and washes-away occluded foreignmaterial.

Another object is to provide a method whereby `foam-like casein israpidly separated `from substantiall-y all liquid with which it lisassociated during processing and is readily received fat #a porous butrelatively high solids content vmaterial. Y Y

These yand other objectsV not specifically 'men-'- tioned will appear tothose yskilled in this lart las 'the *following descriptionproceeds.

In the drawing- -f Figure I is a diagrammatic illustrationVv ofembodiment of the invention.

Figure II is a perspective viewfof an individual tank. y Y Y Figure II'Iis a crosssectional view "of aunit consisting of a, single vesseldivided; into four zones, which is adapted for rotation.

Briefly, the invention is predicated upon the discovery that certainmaterials when given -a foam-like structure can be separated from theirassociated liquid by a crowding action exerted by the material itself,Awhereby to cause the material and liquid to take divergent paths oftravel, and that such materials can be thoroughly washed While theyfloat on a liquid medium without OBB causing the foam to dis-integrateor to lose its buoyancy. Thus, a iiow `pathmay be established consistingof one or more vessels or one or more zones within a single vessel. Insuch a flow path the'vessels or zones are-positioned so that Afioatingmaterial is discharged -'over `the 'wall of one vessel or zone andtravels 'automatically' into 'the ynext vessel or zone of the series,and thereafter is withdrawn from the iiowI path as a spongy, semi-drymass.

The process comprises, by way or a simple specific example, the stepsaccording to which a lacteal fluid containing protein material maybemixed with a coagulating agent und-er cond-it-ions to produce an aeratedmixture, that is lto say, a gaseous-liquid-'solids dispersion. The mix-'ture soproduced is then discharged int-o the first vessel of a seriesof Avessels Vand preferably adjacent one end thereof. A liquid level isestablished and maintained in the vessel substantially 'at the height ofthe lowest wall ofthe vessel. I'he aerated mixture, havingadens-ity'gr-eater than that of partially drained foam due to thepresence of liquid incorporated in the foam by fthe mixing, isintroduced continuously into the yvessel lwhere it exerts a pressure orcrowding action which displaces the lighter partially drained'foamradially outwardly and toward the discharge por'- tion of the vessel.This action forces the vaccumulated foam, which is `separated from the'whey land is iioating on the top thereof, to discharge over theselected wall of the `vessel and cascade downwardly into the nextvvessel positioned at fa slightly lower level. Y

l Figure I of the accompanying- `drawing diagrammatically represents oneprocedure and equipment which can be used 'for practicingithe invention.

Accordingv to the practice illustrated, skim milk and a suitable acidfrom sources vnot shown are, vfed to the open eye of a centrifugal pumpi 40. The feed inlets. are fsosarrangedffthat milk and acid-only mee-t.as Itheyienter `the lmining chamber and the inlets Apermitlthe.pt'irnpto suck air.v The milla-acid, and air 'are mixed lsubstar'i:ltiaily-instantaneously in sucha manner that the lvcoagulated wproteinparticles havewair cells 'entrapped thereinor attached thereto. TheAfrothy mixture produce'dxby themixing .is discharged through pipe 'ilinto 'tank l2. Here., th'ecase'in 'foam I3, which is agaseousliquidsolids fdispersion, separates Vfrom the whey -l--fl withwhich is associated. The whey is discharged from the tank through thepipe I5 which maintains the desired liquid level in the tank I2. Thecasein v:loam vl?, 'moves to the discharge end VHifof vthe tank l2 andis displacedso-` that 'it-lfallscver ftheend wall I1 and slidesfdown anapron i8 and 'into-a, second 'tank 20. Washing'mayor may not have beenYstarted by `spraying water fromfthe nozzles i9 las the casein foam IISapproacheslthe discharge end Il of' tank i2. Ii washing `'lf-ias beenstarted, it obviously Acan be controlled I"so that no wash water can-seep entirely through the foam layer before the casein -foam is displaced `from the tank. Under such condition, washingmay be started earlywithout diluting 'the separated whey. f

Tank l2 is representative of each tank inthe series, differ-ing only inthat in most cases it will be the largest of the group. Tank I2 is arectangular, open tank having three sides of equal height and having itsfourth wall vII of lesser heigiitthan the/other sides. Anfapronjt d5shown positioned in contact with the top ofwall l'l' to prevent thematerialvirom running down theout 'side of the wall I1. Pipe |35yconnects with the liquid discharge opening 15a inthe bottom of tankI`2. it reaches approximately the height of' wall I1-'. The pipedischarges into a receiver- 'leb which in turn connects to pipe 50. Thepipe l5 thus gives one form of automatic liquid level control'.

The casein foam`|3 received in tank 2-0 iioatsvfon the liquid 2l. Theliquid 2| isfcornprised of the y washing liquid plus the solids Washedfrom the casein. The washing liquid yis sup-plied through spray nozzles22 whichapply 'the liquid in a in'e, misty spray to the top ofcaseinfoam'fl.- This sprayed liquid seeps through the foam layer 13, washingthe same, and collects in the bottomloi the tank 2U. In the particularform of apparatus diagrammatically represented in Figure I, which`illustrates a countercurrent washing treatment, the washing medium issupplied to the spray nozzles 22 through pipe 23. The liquid is forcedto the spray nozzles by pump 24 whichobtains the liquid from thesucceeding tank V3Q through pipe 33 and float tank 25.

The salt and lactose enriched washing medium 2| which is accumulated intank 2G is withdrawn through pipe 26. Pipe 2G like its counterpart,namely, pipe I5, is positioned and segmented to maintain a predeterminedliquid level whichin this case is substantially the level of the endwall 21 of the tank 20.

As above pointed out, the casein layer created 'in tanks'20, 30, and 40is displaced or crowded outwardly by the hydrostatic head offoamAaccumulated at the points where the foam falls'into each tank. Thecasein layer thus progressively moves laterally on the surfaceof theliquid longitudinally of the tanks. In eachtank it passes successivelyunder the spray nozzles v'and is A"continuously washed, vafter which itisfentirelydise "placed 'from the tank and falls into 4the nextftank.

Pipe l5 is shown curved upward untilv ForA example, the foam would bedisplaced from tank and be caused to fall into tank 30.

In tank 30, the casein foam I3 iioats on the surface of the washingliquid 34. The foam is further Washed with a Washing liquid, but in thiscase the liquid has a lower concentration of salts and lactose dissolvedtherein than is found in the liquid supplied to tank 20 through nozzles22. This washing liquid is preferably supplied to spray nozzles 35through a pipe 36 by a pump 31. The pump 31 receives the liquid from thesucceeding tanks 40 and 50 through pipes 42 and 52 which feed float tank38.

The level control and pumping system is best described by reference tothe illustration in Figure 2 with reference to tank 30. Tank 30 is arectangular, open tank having three sides of equal height and having itsfourth Wall 3I of lesser height than the other sides. An apron 32 isshown positioned in contact with top of wall 3I to prevent the floatingmaterial -breaking over the Wall from running down the outside of wall 3I. Pipe 33 connects with the liquid discharge opening 33a in the bottomof said tank 30. Pipe 33 is shown curved upward until it reachesapproximately the height of wall 3|, The pipe 33 discharges into areceiver 25. This receiver is connected to pump 24 through pipe 25a. Thepump 24 discharges through pipe 23. The liquid flow in pipe 23 iscontrolled by a 4valve 23a actuated by a level control iioat 23h in thereceiver 25.

The casein foam I3 again drops downwardly and at this point falls intotank 40 where itfloats on the surface of the accumulated wash water 4I.The foam is Washed with water supplied through the nozzles 42.

The casein foam I3 displaced from tank 40 is accumulated in tank 50 forfurther drainage of wash water or for further processing such aspressing and drying. W'nen tank 5?: is utilized as a drainage tank, theonly water introduced into the tank 50, other than that carried in thefoam, is that lubricator drip water which trickles down the side wallsof the vessel. The accumulated quantity of trickle and drainage Water isso small that it is here shown flowing through pipe 52 into receiver 38whose main supply of liquid is from tank 40, although it can be disposedof by any desirable method such as shunting it to a sewer drain.

The wash water supplied to the system is shown as being tap water.Where, for such reasons as alkalinity or the 1ike, the available Wateris unsatisfactory, the wash water may be purified as by ion exchangemethods or the pH adjusted by addition of a small amount of dilute acidor treated in any other suitable manner.

The position and angle of spray issuing from nozzles 22, 35, and 42 canbe utilized to expedite the movement of foam as well as thoroughly towash the material by uniformly distributing the liquid. If the directionof the spray is such that a portion of the liquid strikes the sides ofthe vessels at a point above the casein foam, this liquid runs down thesides of the vessel and acts as a lubricant. The foam thus exhibitslittle or no tendency to stick to the walls. With wall friction markedlyreduced, the foam moves smoothly and uniformly throughout each vessel.

In Figure 3 there isillustrated a modified form of the invention whichcomprises a cylindrical vessel divided into zones including aliquid-foam separation zone and washing zones. In this type of devicethe washing operation may be/rnarkedly trifugal force.

speeded up and a final product obtained which has, roughly, double thesolids content of the product delivered by the flow path system ofFigure 1.

Referring to Figure 3, this casein-foam washer comprises a cylindricalrotating tank 60 which peferably has its longest dimension disposedaxially and vertically. The tank 60 may be formed with an integrallbottom section 6I provided with an axially positioned i'low opening 6Ia.Section 6I is provided with a hollow shaft 62 which forms the flow inletwhich communicates with the inside of the tank 60 through the flowopening Bla. The upper section of the cylindrical tank 60 is open. Theupper circumferential part of tank 60 is connected by means such as therigid spider B3 to a hollow hub section 64 which is axially aligned withshaft 62. Hub section 64 and shaft 62 are seated in suitable bearings65a and 65h. The assembly is rotated by a prime mover, through suitabletransmission means (not shown) such as a coupling, multispeedtransmission gears, belt, or similar device which may be connected toshaft 62, as represented at 62h.

Mounted inside of the tank 60 are four circular rings or partitions 66,61, 68, and 69, which are fixed to the Wall of the cylindrical tank 60by suitable means such as welding. The inner diameters of the rings maybe progressively larger, although this is not necessary. In such event,however, the further the ring is removed from the bottom of the tank 60the larger it is in internal diameter. In the case illustrated. theinner diameter of the ring 69 is almost double that of the ring 66.These partitions divide the rotating member 60 into sections 1U, 1I, 12,and 13.

Each section of the tank has its own level controller drainage pipemarked 14, 15, 16, and 11, respectively. Attached firmly to each drainpipe by pins or spiders, so as to prevent vibration, are the caps 18,19, and 8|, respectively. These caps are so positioned that they preventfoam from entering the drain but do not prevent the iiow of liquid.

Surrounding the cylinder 60 is a housing 82 divided into the fivesections 83, 84, 85, 86, and 81. These sections have individual outlets88, 89, 90, 9|, and 92, respectively.

Extending down through the hub section 64 and through cylinder sections1I, 12, and 13 are perforated cylindrical pipes 1Ia and 12a, theperforations of pipe 1Ia communicating with section 1I and theperforations of pipe 12a com- 'municating with section 12.

From the foregoing description it will be seen that the cylinder may berotated at high speed and a liquid-gaseous dispersion may be introducedinto the cylinder from the bottom through the shaft 62. When thecylindrical tank spins at a speed such as from 500 to 1500 R. P. M., theliquid-gaseous dispersion separates into a foam layer 94 and a wheylayer 95 in section 10. Due to centrifugal force, the foam is at thecore of the cylinder whereas the liquid is on the outside thereofagainst the cylindrical Wall. Liquid 96 sprayed into sections 1I and 1'2from water pipes 1Ia and 12a collects until the level control drainsestablish the desired liquid level. As the operation continues, theseparated foam 94 rises through the center of the cylinder and oatsonthe liquids held to the cylinder Walls by cen- As the foam passesthrough sections 1I and 12, it is contacted by streams of 9 wash watervissuing through the perforations in the.'v centerV pipes 'Hc andv 12a.The Washwater thust permeates:` the; foam layer quickly, due to thecentrifugal force; ill/heyy in section lil, wash water in sectionsv 'Hfand 'l2-5 and drain water in section 'I3A iiow out between theirrespective caps and drainfpipesand spill out through the pipes 14, T5,'Hl andgll into the housing sections 83,; 84, 85 and 86, respectively,where they collect andare individually treated as desired.

The following example may be taken as illustrative. Approximately50,000l pounds per hour or1 whole milk is first putv through foamlessseparators. vThis quantity ot milk is approximately equal tothecapacityeoil about 5` separators. Five thousandpounds-perhourvoi 40%-cream is thus removed,y lea-ving. approximately 45,000- pounds of skimmilk per hour. This quantity of skim milkz and approximately. 400.pounds per hour ofdilute hydrochloric acid, prepared by dilutingone-poundof concentrated, acid totwelve pounds ofsolution, arev eachdivided into duplicate streams. One stream of each material. is. sup.-pliedto. a Z-inch: centrifugal pump,i arranged to maintain the,vconditions. hereinabove dened. Two of thesepumpst arefcapable ofhandling materialat: thev rate, @45,000 pounds of skim milk per hour. Afrothy mixture dischargesfrom the pumpswhich .feed into. the rst of. a.series. of iii/.el tanks. .'Ioy handle milkY at` the above rate, thefirst tanky should.. be approximately 3 feet in. width, 3 feet indepthand. 1,6. feet inlength. Thefrothdischargedintolthisltank rstseparatesinto a whey. layerl and. a foam, layer of, aerated coagulatedcaseincu-rd which. has a. volume of approximately. 73. cubic. feet perhour. The foam layer will be` about 1.8,v inchesthick at the outlet endof the rs't tanks. ,In tanksr 2., and 3v the foam moves countercurrent.tothe Wash, water. In tank 4, the casein foam, washed with aspray ojfresh water.

Washing medium removed.. from tank. 2. has a concentration, otapproximately 3,5 byV weight` of solids Whchisprocessed to. recoyer thesolids.. Y

Casein` foam: displaced from tank.4 usually falls into a. tlr tankwhere, it, floats on. the waterA present therein. This tank,I serves Atoallow .the wash water to drainfrom the foam. At the outltendoitheY fifthtank, the depth of. casein foam isl approximately inches. The foamdisplaced froml tank 5 is a clean white material. ofr bland .flax/or.This. entire casein precipitation and washing operation requires onlythe partial at- EIIQH Of. 0171 .OpelatOIZ- While. various,speciiicembodiments of the ine. vention have been described', it is tobe under,-V stood that the invention is not limited thereto but may bevaried., withinthe scope. ofY the appended.claims,

,1,` Thel method of recovering a solid, capable of,` being convertedinto a floatalole foam, from. itsA associated liquid, which comprisesconverting said solid.. into al'oatable ioam, continuously collectingsaid `foarnand associated. liquidI to form a pool thereof underconditions effecting` a segregationof liquid.. and foam'on the basis ofa response, tof the dierence inA densities of said liquid, and, foam,continuously withdrawing liquid frorn'said `pool atone'point whilepermitting-` newly introduced foamfto exert a crowding and displacingaction,upon.other, foam already present ,in said poolandtherebyfeiecting. a'displace-f-l ruentofV said,l foam, with; respect tosa-idliquid toward a ,secondt point. and.- permitting. said;

10 crowding action to discharge said foamy separate from said liquid andcontinuously collecting the foam so discharged.

2. The method` of separating a solid, capable of being converted into alcatable foam, from its associated liquid, which comprises convertingsaid-'solid interak iioatable foam, continuously collectingsaid foamvand associated liquid to form' a pool thereof' under conditionspermitting rfloating of said foam anda consequent segregation of theliquid and foam, continuouslyV withdrawing in one direction liquidfromsaid pool at a point below the surface thereofA While permitting'newlyintroduced foam to. exert a crowding and disv placing action uponother'foamA alreadyl present on the-surface of said pool and therebyApermitting saidcrowding action to rdisplace said foam onthesurface inanother direction'untilfsaid displaced' foam is-:separated from saidliquid, and continuously collecting foam. so displaced.'

3. The process off claim 2, further character# ized that't-he' foam onsaidv pool is sprayed with washing liquid during said `displacementthereof.

d. The: process of' claim 2; further charactere izedi-n that-saiddisplaced foam is collected 'in' a second pool comprising washingliquid,and' sa-d foam* is continuously introduced: in said second pool,l iswashed-by spraysbf wash water proL jectedffrom above. and:v a similardisplacement and separation Ao'ioam; and withdrawal of liquidiscausedto'oceur.

^ 5. The process` donned in. claim 4 further characterized in that apluralityof washing operationsV are'.A conducted ina plurality ofn poolsof washing liquid, each successive pool being main'- tainedat a levelslightlyV below theother whereby said-foam;- when displaced. laterallyfrom one pool, is. displaced bygravity onto the next pool.

6. The= process of. claim 5, further` characterizedfinfthat the. washingliquid used in said washing 'operationss'isf reused vbypassing4 the samefrom 4onepooll intheseries' orvr poolsv to' the next preceding p'oolvand sov on toproviderfa.v now path? fon thewashing liquid which iscounter current to thepathfot saidfoam, and continuing suchcountercurrent vre.using,I 'of said 'washing liquid to: an:extentsu-icient to produce aconf centrationr'of solids-therein ofapredetermined value. A f

'7. The method of separating solids'from associatedf liquid; which4-comprises rsticonventing the solidsxintof a relatively stable-'foamhavinga density less than.A that oily the liquid. with which: itisassociated, introducing thesame into there.` ceiving end of. ai iiowpath andL permittingthe sameV` tofsepara-te into liquid phase. andafloating foam phase;` andi displacing said floating foam phase-laterallyoverthe suriacefoftheass ciaited liquid* and ydischargingA saidF :foamyphase separate fronr said'liquid phasewhile v'vitlniraw-z ing liquidfrom a point below' the? l'evel of said liquid: y

8? Thefmeth-od'of separating? solids from asso#Y ciated liquid, whichcomprisesVv rst converting the-solids into a relativel'yfst'abl'e foamhaving a' density less than that of 'theliquidwith which itfisassociated v vhereb'yv separation into a liquid phase and a foam phaseoccurs, introducingthe same into the receiving end of a flow path,displacing said. floatingfoam phaselaterally over the surface of theassociated liquid and thereby separating said foam.. phase from, said.liquid phase while withdrawing liquid from a pointbef. 1 0-Wtheflevelfof said. liquid. and. spraying .the

separatedfoam with washing liquid as said foam is forced across theliquid surface of the flow path by the pressure exerted by freshlyintroduced dispersion, and collecting the discharged foam.

9. The method of recovering a relatively stable foam having a densityless than that of the liquid with which it is associated, whichcomprises introducing and rotating a gaseous liquid dispersion at highspeed in a series of centrifuging zones, establishing a controlled depthof liquid in said zones. forcing the floating foam through the zones bythe pressure of freshly introduced foam, and collecting the washed foamdischarged from said centrifuging zones.

10. The method of Washing a relatively stable foam having a density lessthan that of the medium with which it is associated, which comprisescontinuously introducing a dispersion which separates into a liquidphase and a floating foam phase into the receiving end of a flow path,spraying the separated foam with washing medium as said foam is forcedacross the liquid surface of the flow path by the pressure exerted byfreshly introduced dispersion, and collecting the discharged foam.

1l. The method of Washing a relatively stable foam having a density lessthan that of the medium with which it is associated, which comprisescontinuously introducing a dispersion which separates into a liquidphase and a floating foam phase into the receiving end of a flow path inwhich the dispersion is subjected to centrifugal force, spraying thefoam which floats on a predetermined depth of liquid held adjacent theiiow path periphery as said foam is forced across the liquid surface bythe pressure of freshly introduced dispersion, and continuously removingseparately the foam and separated liquid.

12. The method of Washing a relatively stable foam having a density lessthan that of the medium with which it is associated, which comprisescontinuously introducing a dispersion which separates into a liquidphase and a floating foam phase into the receivingl end of the first ofa group of sequentially arranged Zones, said zones being positioned insuch manner that the foam displaced from one zone drops to and floats onthe liquid in the next zone, continuously forcing the foam across theliquid surface and out of each zone by the pressure of freshlyintroduced dispersion, continuously spraying the foam With Washingmedium while said foam traverses each zone, and continuously collectingthe Washed zone floats on the liquid in the next zone, continuouslyforcing the foam across the liquid surface and out of each zone by thepressure of freshly introduced foam, spraying the foam with Washingmedium while said foam traverses the zones intermediate the rst and lastZones, and continuously collecting the Washed and substan tially drainedfoam discharged from the last zone.

14. The method of washing a relatively stable foam having a density lessthan that of thev medium with which it is associated, which comprisescontinuously introducing a foam and associated liquid medium into thereceiving end of the first of a group of sequentially arranged zones andseparating therein the foam and associated liquid medium into a liquidphase and a foam phase, said zones being positioned in such a mannerthat the foam displaced from one zone floats on the liquid in the nextzone, continuously forcing the foam across the liquid surface and out ofeach zone by the pressure of freshly introduced foam, spraying the foamas it traverses each zone with the drained wash Water from the next zoneinto which the foam travels, and continuously collecting the washed andsubstantially drained foam discharged from the last zone.

15. The method of washing aerated coagulated protein material having adensity less than water, which comprises continuously introducing agaseous-liquid dispersion of protein material which separates into aliquid and a foam phase into the receiving end of the first group ofse-g quentially arranged zones, said zones being positioned in suchmanner that the foam phase displaced from one zone iicats on the liquidsurface and out of each zone by the pressure of freshly introducedmaterial, continuously spraying the foam with washing medium while saidfoam traverses each zone, and continuously collecting the Washed foamdischarged from the last zone.

16. The method of Washing coagulated aerated protein material having adensity less than water, which comprises continuously introducing agaseous-liquid dispersion of protein material which separates into aliquid and a floating curd into the receiving end' of the iirst of asuccession oi' descending zones, continuously forcing the floating curdto the discharge point of each zone and continuously displacing saidcurd therefrom by the pressure of freshly introduced curd, continuouslymoving the floating curd through and out of each zone in turn whilecontinuously spraying the floating curd with Washing medium, andcontinuously discharging the floating curd to iinal drainage andcollection.

17. The method of Washing an aerated casein foam coagulated from milk,which comprises continuously introducing a gaseous-liquid dispersionwhich separates into a whey liquid and a floating casein curd into thereceiving end of the first of a group of sequentially and cooperativelyarranged zones, said zones being positioned in such manner that thecasein curd displaced from one zone floats on the liquid in the nextzone, continuously forcing the floating curd across the liquid surfaceand out of each zone by the pressure of freshly introduced floatingcurd, continuously spraying the foam traversing the zones intermediatethe iirst and last zones with the drained wash water accumulated in thesucceeding zone in the sequence, and continuously collecting the washedand substantially drained casein curd discharged from the last zone.

18. The method of washing a relatively stable foam having a density lessthan Water, which comprisesv continuously introducing and rotating agaseous-liquid dispersion of protein material at high speed in a seriesof centrifuging zones, separating the liquid and foam by centrifugalforce, continuously forcing the foam through the zones by the pressureof freshly introduced foam, continuously spraying the foam 13 withwashing medium while said foam traverses each zone intermediate the rstand last zone, continuously removing liquid and Wash water from therotating zones, and continuously co1- lecting the washed foam dischargedfrom the last zone.

19. The method of washing a, relatively stable foam having a densityless than that of the liquid with which it is associated, whichcomprises introducing and rotating a gaseous-liquid dispersion in a,succession of high-speed rotating zones to effect phase separationbetween foam and liquid, controlling the level of liquid in said zonesby the controlled drainage of the liquid therein, forcing the floatingfoam through successive zones by the pressure of freshly introducedfoam, spraying the foam with washing medium while the foam traversessaid zones, and collecting the washed foam discharged from the lastrotating zone.

PAUL F. SHARP. JOHN B. SHIELDS.

14 REFERENCES orrnn The following references are of record in the file,of this patent:

UNITED STATES PATENTS Number Name Date 793,808 Sulman et a1 July 4, 19051,087,094 Berrigan Feb. 10, 1914 1,297,372 Loventhal Mar. 18, 19191,420,139 Peck June 26, 1922 1,442,306 Stonebraker Jan. 16, 19231,638,977 Avery Aug. 16, 1927 1,683,262 Richter Sept. 4, 1928 1,800,965Spalding Apr. 14, 1931 1,838,475 Buswell D ec. 29, 1931 2,184,115 CokeDec. 19, 1939 2,190,136 Oberg Feb. 13, 1940 2,209,694 Harford July 30,1940 2,236,895 Court Apr. 1, 1941 2,281,609 Walter May 5, 1942 2,368,919Fritzberg Feb. 6, 1945 2,381,369 Sconce Aug. 7, 1945 2,410,633Counselman Nov. 5, 1946 2,446,655 Lawrason Aug. 10, 1948

1. THE METHOD OF RECOVERING A SOLID, CAPABLE OF BEING CONVERTED INTO AFLOATABLE FOAM, FROM ITS ASSOCIATED LIQUID, WHICH COMPRIESE CONVERTINGSAID SOLID INTO A FLOATABLE FOAM, CONTINUOUSLY COLLECTING SAID FOAM ANDASSOCIATED LIQUID TO FORM A POOL THEREOF UNDER CONDITIONS EFFECTING ASEGREGATION OF LIQUID AND FOAM ON THE BASIS OF A RESPONSE TO THEDIFFERENCE IN DENSITIES OF SAID LIQUID AND FOAM, CONTINUOUSLYWITHDRAWING LIQUID FROM SAID POOL AT ONE POINT WHILE PERMITTING NEWLYINTRODUCED FOAM TO EXERT A CROWDING AND DISPLACING ACTION UPON OTHERFOAM ALREADY PRESENT IN SAID POOL AND THEREBY EFFECTING A DISPLACEMENTOF SAID FOAM WITH RESPECT TO SAID LIQUID TOWARD A SECOND POINT ANDPERMITTING SAID CROWDING ACTION TO DISCHARGE SAID FOAM SEPARATE FROMSAID LIQUID AND CONTINUOUSLY COLLECTING THE FOAM SO DISCHARGED.